1. Field of the Invention
The invention relates to a rotation transmitting apparatus having two rotary shafts that are fitted together so as to be slidable relative to each other in the axial direction and so as to be engageable with each other in the rotational direction, a vehicle steering system, and an intermediate shaft.
2. Description of Related Art
Japanese Patent Application Publication No. 2009-168144 (JP 2009-168144 A) describes a rotation transmitting apparatus in which a spline shaft is fitted to a spline sleeve so as to be slidable relative to the spline sleeve in the axial direction and so as to be engageable with the spline sleeve in the rotational direction. JP 2009-168144 A describes a driving force transmission apparatus having protrusions 6PR formed at radially outer ends of ridges so as to extend in the axial direction, and protrusions 6RB formed at axially opposite ends of the ridges so as to extend continuously in the circumferential direction.
The protrusions 6PR and the protrusions 6RB have the effect of decreasing a radial backlash between the spline sleeve and the spline shaft, thereby allowing the spline shaft to smoothly slide relative to the spline sleeve.
The protrusions 6PR have the function of decreasing the radial backlash, but do not have the function of absorbing a backlash in the rotational direction. Therefore, it is not possible to smoothly transmit the rotation of the spline sleeve to the spline shaft. Further, the protrusions 6RB do not have the function of absorbing the backlash in the rotational direction. Therefore, it is not possible to smoothly transmit the rotation of the spline shaft to the spline sleeve.